Optical device inspecting apparatus

ABSTRACT

To provide an optical device inspecting apparatus which can be set to take many objects at one time more freely compared with conventional apparatuses, and can accurately inspect even an optical device wherein an optical sensor is offset from a microlens. Provided is an optical device inspecting apparatus having a probe card unit and a lens unit. The probe card unit is provided with a main substrate, a guide plate and a probe. The guide plate is provided with a plurality of probe inserting holes. The probe is inserted into the probe inserting hole on the guide plate and fixed. The leading end portion of the probe protruding from the inserting hole has a shape of a cantilever. The lens unit is arranged at the opening on the main substrate, and makes light applied to an inspecting object incline as the light goes further from the optical system.

This is a continuation of U.S. Pat. No. 8,159,659 issued on on Apr. 17,2012, which was a US National Stage Application of PCT applicationnumber PCT/JP2007/071846 filed on Nov. 9, 2007, and priority is claimedthereto.

FIELD OF THE PRESENT INVENTION

The present invention relates to inspection devices for optical devicesthat are used to inspect so-called optical devices such as photoelectricconversion devices including an image sensor and a solid-state imagesensor.

BACKGROUND OF THE PRESENT INVENTION

Inspection of so-called optical devices such as photoelectric conversiondevices including an image sensor and a solid-state image sensorrequires measurement of characteristics by projecting light onto animage-sensor member. For example, the inspection of a solid-state imagesensor is performed as follows:

A chip of solid-state image sensor 1 has a side length of ten mm or lessand is provided with a sensing area 2 in the middle of the chip surface.The sensing area 2 is embedded with hundreds of thousands to millions ofoptical sensors, and formed along the four sides of the sensing area 2is an electrode pad 3 (refer to FIG. 1).

To inspect the operation of the solid-state image sensor 1, light isprojected onto the sensing area 2, and an electrical characteristiccaused by the incident light is evaluated by measuring electricalsignals extracted from the electrode pad 3.

Such inspection devices include a device comprising a cantilever-typeprobe card that includes a lens unit mounted thereto. JapaneseUnexamined Patent Application Publication No. 11-26521 discloses anexample of such a conventional inspection device.

Japanese Unexamined Patent Application Publication No. 5 11-26521discloses an inspection device 18 and an optical device 17 that areintegrated. The inspection device 18 is a probe card 16 having, in itscenter, an opening for projecting light and comprises a cantilever-typeprobe 15 (refer to FIG. 6).

In designing a probe card comprising the conventional cantilever-typeprobe used in the above-described inspection device, its structure makesit impossible to arrange the inspection area to be close to theinspection device, and therefore, respective probe-supporting membersmust be separately provided on a substrate.

In addition, one-by-one measurement of devices on the wafer results in alengthy inspection time, and therefore, probe cards are required tomeasure a plurality of devices at a time. To deal with the requirement,a probe card comprising the vertical-type probe is proposed.

Here, the optical device comprises a microlens and an optical sensor. Inthe case of a solid-state image sensor of one centimeter square,hundreds of thousands to millions of optical sensors are embedded.Microlenses are provided corresponding to the optical sensors in orderto project light onto the optical sensor more effectively.

In the case of an imaging camera using such an optical device, thereexists an exit pupil determined by the aperture of the lens. The fartherthe exit pupil from the center of the optical system, the lower theangle of incident that light will make with the optical sensor.Therefore, corresponding to the angle, the optical sensor is offsetoutwardly from the microlens as the exit pupil becomes farther from thecenter.

(Patent Document) Japanese Published Unexamined Patent Application No.H11-26521

SUMMARY OF THE PRESENT INVENTION Problems to be Solved by the Invention

In inspecting the output sensitivity of the sensor of an optical devicewhose optical sensor is offset from the microlens as described above, itis problematic that if a collimated beam is used for the inspection, theoutput sensitivity of a sensor that is offset from the device,especially of a sensor that is greatly offset, represents low, andtherefore, even a device of a good quality is determined to bedefective.

To deal with the problem of the needle shade cast on projected lightwhich affecting the measurement in taking a plurality of chips, and theproblem of projected light affecting adjacent chips because of aprojection area 21 being circle while the sensing area 2 is square asillustrated in FIG. 7, the conventional devices take a plurality ofchips in diagonal direction and comprise a light reflection plate forprojected light.

There are problems, however, with the conventions devices in that someeight chips are the maximum of the number of chips to be taken and inthat enlarging the opening to take a plurality of chips causes warp ofthe substrate and slippage of the needle.

One object of the present invention is to provide an inspection devicefor an optical device allowing for taking a plurality of chips morefreely than the conventional devices and enabling accurate inspection ofoptical devices whose optical sensor is offset from the microlens.

Means for Solving the Problems

According to the present invention, an inspection device for an opticaldevice including a plurality of optical sensors in a sensing areacomprises a light source for projecting light onto the optical devicefor inspection; wherein a pupil lens is provided between the lightsource and the sensing area, the pupil lens making the angle of incidentof projected light lower as the pupil lens becomes farther from thecenter of the optical system.

According to the present invention, an inspection device for an opticaldevice comprises: a probe card unit and a lens unit; wherein the probecard unit includes a main substrate, a guide plate and a probe; the mainsubstrate and the guide plate being provided with an opening; the guideplate being fixed to a certain location of the main substrate andprovided with a plurality of probe insertion holes; the probe beingdisposed and fixed in the probe insertion hole of the guide plate, andhaving a end part projecting out from the insertion hole in the shape ofa cantilever; the lens unit including a pupil lens, being disposed inthe opening provided in the main substrate, and making the angle ofincident of light that is projected onto an device being inspected loweras the pupil lens becomes farther from the center of the optical system.

Preferably, the guide plate is provided with a groove, the probeinsertion hole is disposed in the bottom of the groove, and the probe isfixed in the groove with resin.

Preferably, the inspection device further comprises a light blockingmember for blocking a beam of light projected by the lens unit onto theprobe.

Preferably, the light blocking member is the guide plate.

ADVANTAGEOUS EFFECTS OF THE PRESENT INVENTION

According to the present invention, an inspection device for an opticaldevice including a plurality of optical sensors in a sensing areacomprises a light source for projecting light onto the optical devicefor inspection; wherein a pupil lens is provided between the lightsource and the sensing area, the pupil lens making the angle of incidentof projected light lower as the pupil lens becomes farther from thecenter of the optical system thereby allowing for inspection of theoptical device under the conditions of the actual use.

According to the present invention, an inspection device for an opticaldevice comprises: a probe card unit and a lens unit; wherein the probecard unit includes a main substrate, a guide plate and a probe; the mainsubstrate and the guide plate being provided with an opening; the guideplate being fixed to a certain location of the main substrate andprovided with a plurality of probe insertion holes; the probe beingdisposed and fixed in the probe insertion hole of the guide plate andhaving a end part projecting out from the insertion hole in the shape ofa cantilever; the lens unit including a pupil lens, being disposed inthe opening provided in the main substrate, and making the angle ofincident of light that is projected onto an device being inspected loweras the pupil lens becomes farther from the center of the optical systemthereby enabling inspection of the optical device under the conditionsof actual use, which results in a more accurate inspection.

In addition, the guide plate is provided with a groove, the probeinsertion hole is disposed in the bottom of the groove, and the probe isfixed in the groove with resin thereby improving the workability infixing the probe.

Further, the inspection device further comprises a light blocking memberfor blocking a beam of light projected by the lens unit onto the probethereby eliminating the harmful effects to adjacent chips.

Further, the light blocking member is the guide plate therebyeliminating the need of an extra light reflection plate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 (a) is a plan view of an entire solid ‘state image sensor that isan optical device and its enlarged partial plan view, and FIG. 1 (b) isa plan view of one of solid, state image sensors extracted;

FIG. 2 is a schematic cross sectional view of an inspection device foran optical device;

FIG. 3 is a cross sectional view of the entire inspection device for anoptical device;

FIG. 4 is an enlarged view of part a illustrated in FIG. 2;

FIG. 5 is an overall view of a probe;

FIG. 6 is a schematic cross sectional view of the conventionalinspection device for an optical device; and

FIG. 7 is a plan view of the projection area given by the conventionalinspection device for an optical device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will now be described more specifically withreference to the drawings. FIG. 2 is a schematic view of an inspectiondevice for an optical device according to the present invention. FIG. 3is a cross sectional view of the entire inspection device for an opticaldevice.

An inspection device 4 for an optical device according to the presentinvention comprises a probe card unit 5 and a lens unit 6. The probecard unit 5 and the lens unit 6 are integrated.

The probe card unit 5 comprises a main substrate 8, a guide plate 9 anda probe 7. The main substrate 8 and the guide plate 9 are provided withan opening. The guide plate 9 is fixed to a certain location of the mainsubstrate 8 and provided with a plurality of probe insertion holes 10.

An insertion part 22 of the probe 7 is disposed and fixed in the probeinsertion hole 10 provided in the guide plate 9. An end part 23 of theprobe 7 projects out from the probe insertion holes 10. Here, asillustrated in FIG. 5, while the insertion part 22 of the probe 7 is inthe shape of a vertical-type probe, the end part 23 is in the shape of acantilever as the end part 23 bends at a point a little out from theguide plate 9 and extends 7 towards the opening in the guide plate 9.The end of the probe 7 is the needle tip. As described here, the probe 7according to the present invention takes the shape of both avertical-type probe and a cantilever-type probe.

The end part 23 of the probe 7 is short enough to be hidden beneath theguide plate 9 thereby solving the problem of light reflected from theprobe.

The probe insertion hole 10 is disposed in the bottom of a groove 20provided in the guide plate 9. The probe 7 is fixed in the groove 20with resin 21. The probe 7 is fixed with resin with its insertion part22 projecting a little out from the probe insertion hole 10 in the guideplate 9. Especially, it is preferred that the projecting part of theinsertion part 22 be fixed with resin up to the point where the end part23 starts to bend thereby achieving a high needle pressure.

Here, the cantilever-type probe is a probe that takes, from the partmounted to a substrate to the needle tip, the shape of a cantilever. Thecantilever type probe is fixed to a substrate or the like by connectionmeans such as soldering, and its cantilever shape allows it to changethe shape in the lengthwise direction in response to external force. Onthe other hand, the vertical-type probe is a probe that is in the shapeof a substantially straight line. The vertical-type probe is mountedperpendicularly to a substrate by means of a guide plate or the like,and an elastic part provided allows it to change the shape in thelengthwise direction in response to external force. The probe 7according to the present invention is 8 characterized in that it takesthe shape of both types of probes.

The probe 7 is disposed in a through hole provided in the main substrate8. The probe 7 is fixed to the upper end of the through hole with solderand electrically connected to a trace on the main substrate 8 inside thethrough hole.

The pitch of each through hole in the main substrate 8 is greater thanthat of each probe insertion hole 10 in the guide plate 9, andtherefore, the insertion part 22 of the probe 7 is a little bent asillustrated in the drawing. The probe 7, for example, is formed ofrhenium tungsten, has a 10 diameter of 80 pm, and is disposed at a pitchof 120 pm.

The guide plate 9 is fixed to a certain location of the main substrate 8with a spacer 24 interposed there between. The spacer 24 is a unitholder and formed of stainless steel or ironic metal. The guide plate 9is ceramic.

The present embodiment employs a reinforce panel 12 to reinforce themain substrate 8. The reinforce panel is formed of stainless' steel orironic metal.

The lens unit 6 comprises a pupil lens 11. As the light source, acollimated beam generating less heat such as a LED is used. The pupillens 11 employed here solves the problems with the conventionalinspection devices for an optical device, which determine an opticaldevice of a good quality as defective due to the sensor outputsensitivity, which represents low because of the collimated beam used,of the optical device whose optical sensor is greatly offset from themicrolens.

More specifically, by using the pupil lens 11 that is the same exitpupil as that used in an imaging camera comprising an optical device,recreated is incident light whose angle with the optical device of theimaging camera becomes lower as the exit pupil becomes farther from thecenter of the optical system thereby allowing for inspection under thesame conditions in which the optical device is actually used.Accordingly, by projecting light properly onto the optical sensor, theproblems that arise in inspecting the sensor output sensitivity of anoptical device whose optical sensor is offset from the microlens issolved, which allows for more accurate inspection as a device of goodquality is no longer determined as defective.

How to inspect an optical device by the inspection device 4 for anoptical device according to the present invention will now be explained.In the present embodiment, the solid-state image sensor 1 that is anoptical device illustrated in FIG. 1 is inspected at ambient temperatureto 60° C.

As illustrated in FIG. 4, light from a light source 14 is diffusedthrough the pupil lens 11 of the lens unit 6 and projected onto theoptical device that is being measured. At this time, the light passedthrough the lens unit 6 passes through the opening provided for theguide plate 9. The light projection area is, however, substantially thesame as the sensing area 2 of the solid-state image sensor 1 becausepart of the light is blocked by the guide plate 9, and therefore,adjacent solid-state image sensors 1 are little affected.

As described above, the probe 7 makes contact with the electrode pad 3with light projected onto the sensing area 2, which allows formeasurement of electrical signals extracted from the electrode pad 3thereby performing inspection of the solid-state image sensor 1.

As described above, instead of a light reflection plate or the like thatthe conventional inspection devices require, the inspection device 4 foran optical device according to the present invention comprises the guideplate 9 part of which blocks a beam of light as a light blocking memberthereby enabling restriction of the projection area.

The inspection device 4 for an optical device according to the presentinvention comprises, as one unit, a plurality of devices, the structure10 of which is illustrated in FIG. 2, arranged in a straight line. Theunit is mounted to a substrate with a holder. In addition, in arrangingthe above-mentioned unit, the surface of the unit is made even by meansof the unit holder, and the balance of the entire unit is managed byadjusting the balance of the unit with respect to the main substrate.

As described above, the inspection device for an optical deviceaccording to the present invention comprises a lens unit including apupil lens thereby enabling inspection of an optical device under theconditions of actual use, which results in a more accurate inspection.Further, the inspection device for an optical device according to thepresent invention comprises a probe that takes the shape of both of thevertical-type probe and the cantilever-type probe thereby overcomingoutstanding problems with each type of probe and making use ofadvantages of each type of probe, which allows the measurement area tobe set at will. Different from the conventional inspection devices, theinspection 11 device for an optical device according to the presentinvention comprises a probe card unit including a lens unit integratedthereto, instead of being merely combined with, which alleviateslimitations on designing held by each part of the conventional devicesand allows for an inspection device with improved accuracy.

EXPLANATION OF REFERENCE NUMERALS

1: Solid' State Image Sensor; 2: Sensing Area; 3: Electrode Pad; 4:Inspection Device for Optical Device; 5: Probe Card Unit; 6: Lens Unit;7: Probe; 8: Main Substrate; 9: Guide Plate; 10: Probe Insertion Hole;10 11: Pupil Lens; 12: Reinforce Panel; 13: Wafer; 14: Light Source; 15:Cantilever-Type Probe; 16: Probe Card; 17: Optical Device; 18:Inspection Device; 20: Groove; 21: Resin; 22: Insertion Part; 23: EndPart; and 24: Spacer.

1) A probe, comprising: a straight vertical portion; a tip cantileverportion; wherein a cross-section of said straight vertical portion is arectangle; and said tip cantilever portion is a planar shape in a sameplane as said straight vertical portion. 2) A probe card unitcomprising: a main substrate; probes; wherein said main substrate isprovided with square fixing holes to be fixed with one end of saidprobes at a predetermined position thereon; wherein said probes arearranged vertically; wherein said probes are fixed in said fixing holes;wherein said probes have a linear vertical portion; wherein said probeshave one end portion; wherein said vertical portion has avertically-extended shape and has a rectangle in a cross-sectionalshape; and wherein said one end portion has a planer cantilever-typeshape, and the planer face of said one end portion and a face of thevertical portion are flush with each other. 3) The probe card unit ofclaim 2, wherein said probe is manufactured via MEMS technology. 4) Theprobe card unit of claim 2, further comprising a guide plate configuredto restrict the vertical position of said probes to said predeterminedposition. 5) The probe card unit of claim 4, wherein said guide plate isprovided with rectangular guide holes configured to align with saidrectangle in a cross-sectional shape. 6) The probe card unit of claim 3,further comprising a guide plate configured to restrict the verticalposition of said probes to said predetermined position. 7) The probecard unit of claim 3, wherein said guide plate is provided withrectangular guide holes configured to align with said rectangle in across-sectional shape. 8) The probe card unit of claim 4, wherein saidprobe is manufactured via MEMS technology. 9) The probe card unit ofclaim 4, wherein said guide plate is provided with rectangular guideholes configured to align with said rectangle in a cross-sectionalshape. 10) The probe card unit of claim 5, wherein said probe ismanufactured via MEMS technology.